Co-precipitation of calcium carbonate and curcumin in an ethanol medium as a novel approach for curcumin dissolution enhancement

The scope of the present work was to prepare a CaCO3 based solid dispersion (SD) formulation to enhance dissolution rate of a water insoluble drug curcumin. The formation of SD was carried out in ethanolic CaCl2 solution by a facile CO2 diffusion method, proposed to disperse curcumin into CaCO3 during its crystal nucleation and growth. This pathway enabled gentle interaction between curcumin and CaCO3, allowing for approximately 100% drug entrapment independent of curcumin concentration. In addition, the drug content of curcumin in as-formed SD was estimated to be parallel to the increased curcumin concentration in ethanol. The SDs were subsequently characterized by various analytical techniques including X-ray diffraction (XRD), zeta potential analysis, and scanning electron microscopy (SEM). Besides, the dissolution study revealed a remarkable enhancement of curcumin dissolution, highlighted with over 90% of loaded curcumin dissolved in 25 min. In addition, the CaCO3 carrier was shown to preserve antioxidant activity of curcumin during SD preparation and after 6 months storage. Taken together, this novel SD preparation pathway seems to be a promising option for preparing oral administrated formula for water insoluble drugs.